Heretofore, when charging refrigeration systems with refrigerant, normally the amount of refrigerant that is fed into the system is measured by flow meters. One problem with using flow meters is that temperatures and various atmospheric conditions affect the refrigerant, and as a result it is difficult to load the refrigeration system with consistent and accurate amounts of refrigerant.
Attempts have been made to preload cylinders carried on top of scales so that a predetermined weight of refrigerant can be loaded from the cylinder into the refrigeration systems. Normally, these systems utilize spring operated scales which are not highly accurate when they are being used to weigh a predetermined amount of refrigerant as is flowing from the cylinder so as to cut off the flow of refrigerant when a predetermined weight has been charged into the refrigeration system.
Examples of various types of refrigerant charging and weighing devices are disclosed in U.S. Pat. Nos. 2,746,258; 3,076,319 and 3,400,552.